Results from an idealized three-dimensional baroclinic life-cycle model are interpreted in a potential vorticity (PV) framework to identify the physical mechanisms by which frictional processes acting in the atmospheric boundary layer modify and reduce the baroclinic development of a midlatitude storm. Considering a life cycle where the only non-conservative process acting is boundary-layer fri...

The role of large-scale atmospheric eddies and the mean meridional circulation (the Ferrell cell) in explaining the observed net heating of the ocean in the latitude band of the Antarctic Circumpolar Current (ACC) is examined in the NCEP-NCAR reanalyses. Emphasis is placed on processes limiting evaporative cooling rather than on on those promoting radiative heat gain. It is found that the moist...

The processes regulating the climatology and annual cycle of the tropical tropopause layer (TTL) and cold point are not fully understood. Three main drivers have been identified: planetary scale equatorial waves excited by tropical convection, planetary scale extratropical waves associated with the deep Brewer-Dobson Circulation, and synoptic scale waves associated with the midlatitude storm tr...

Motivated by observations of thermohaline staircases in the midlatitude oceans, we have conducted direct numerical simulations (DNS) of the evolution of a diffusively unstable shear layer. This flow supports both KH and salt sheet instabilities, and we wish to see how the two mechanisms work together to drive the transition to turbulence. The main controlling parameters are the bulk Richardson ...

one of the world's major mineral dust source regions lies along the border between iran and afghanistan. in this studyit is hypothesized that a low-level jet may play in role in generating the intensity of this source region. the presence of alow-level jet east of the seistan mountains is documented here for the first time. the jet exists mainly from may toseptember and has a core at 850 mb. ma...

Data collected in midlatitude cirrus clouds by instruments on jet aircraft typically show particle size distributions that have distinct distribution modes in both the 10–30-mm maximum dimension (D) size range and the 200–300-mm D size range or larger. A literal interpretation of the small D mode in these datasets suggests that total concentrations Nt in midlatitude cirrus are, on average, well...

The east-west striped pattern of clouds in Jupiter's weather layer is accompanied by a zonal flow containing 12 eastward-going jet streams alternating in latitude with westward-going jet streams. Based on theory, simulation and observations of the Earth's oceans and atmosphere, it is conjectured that Jupiter's weather layer is made of bands of constant potential vorticity (PV), where the interf...

The influence of clouds on the large-scale atmospheric circulation is examined in numerical simulations from an atmospheric general circulation model run with and without atmospheric cloud radiative effects (ACRE). In the extratropics of both hemispheres, the primary impacts of ACRE on the circulation include 1) increases in the meridional temperature gradient and decreases in static stability ...

The eddy-driven jet is located in the midlatitudes, bounded on one side by the pole and often bounded on the opposite side by a strong Hadley-driven jet. This work explores how the eddy-driven jet and its variability persist within these limits. It is demonstrated in a barotropic model that as the jet is located at higher latitudes, the leading mode of variability of the jet changes from a meri...